Drug interactions between Effexor and Phenergan

Interactions between your drugs

Moderate

promethazine venlafaxine

Applies to: Phenergan (promethazine) and Effexor (venlafaxine)

Using promethazine together with venlafaxine can increase the risk of an irregular heart rhythm that may be serious and potentially life-threatening, although it is a relatively rare side effect. You may be more susceptible if you have a heart condition called congenital long QT syndrome, other cardiac diseases, conduction abnormalities, or electrolyte disturbances (for example, magnesium or potassium loss due to severe or prolonged diarrhea or vomiting). Talk to your doctor if you have any questions or concerns. You should seek immediate medical attention if you develop sudden dizziness, lightheadedness, fainting, shortness of breath, or heart palpitations during treatment with these medications, whether together or alone. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

Drug and food interactions

Moderate

venlafaxine food

Applies to: Effexor (venlafaxine)

Alcohol can increase the nervous system side effects of venlafaxine such as dizziness, drowsiness, and difficulty concentrating. Some people may also experience impairment in thinking and judgment. You should avoid or limit the use of alcohol while being treated with venlafaxine. Do not use more than the recommended dose of venlafaxine, and avoid activities requiring mental alertness such as driving or operating hazardous machinery until you know how the medication affects you. Talk to your doctor or pharmacist if you have any questions or concerns.

See Also

Drug Interaction Classification

The classifications below are a guideline only. The relevance of a particular drug interaction to a specific patient is difficult to determine using this tool alone given the large number of variables that may apply.

Major

Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.

Moderate

Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.